diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8491e7dc14..f876bb3972 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,9 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Removed the `Features` API which is not supported by OpenSearch from the low-level client ([#331](https://github.com/opensearch-project/opensearch-net/pull/331))
 - Removed the deprecated low-level `IndexTemplateV2` APIs in favour of the `ComposableIndexTemplate` APIs ([#437](https://github.com/opensearch-project/opensearch-net/pull/437))
 
+### Fixed
+- Fix `HttpConnection.ConvertHttpMethod` to support `Patch` method ([#489](https://github.com/opensearch-project/opensearch-net/pull/489))
+
 ### Dependencies
 - Bumps `Microsoft.CodeAnalysis.CSharp` from 4.2.0 to 4.6.0
 - Bumps `NSwag.Core.Yaml` from 13.19.0 to 13.20.0
@@ -130,4 +133,4 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 [1.6.0]: https://github.com/opensearch-project/opensearch-net/compare/v1.5.0...v1.6.0
 [1.5.0]: https://github.com/opensearch-project/opensearch-net/compare/v1.4.0...v1.5.0
 [1.4.0]: https://github.com/opensearch-project/opensearch-net/compare/v1.3.0...v1.4.0
-[1.3.0]: https://github.com/opensearch-project/opensearch-net/compare/v1.2.0...v1.3.0
\ No newline at end of file
+[1.3.0]: https://github.com/opensearch-project/opensearch-net/compare/v1.2.0...v1.3.0
diff --git a/src/OpenSearch.Net/Connection/HttpConnection.cs b/src/OpenSearch.Net/Connection/HttpConnection.cs
index 57c63a34af..dfb8506fd9 100644
--- a/src/OpenSearch.Net/Connection/HttpConnection.cs
+++ b/src/OpenSearch.Net/Connection/HttpConnection.cs
@@ -27,7 +27,6 @@
 */
 
 using System;
-using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Diagnostics;
@@ -70,6 +69,8 @@ public class HttpConnection : IConnection
 			+ $" please set {nameof(ConnectionConfiguration.ConnectionLimit)} to -1 on your connection configuration/settings."
 			+ $" this will cause the {nameof(HttpClientHandler.MaxConnectionsPerServer)} not to be set on {nameof(HttpClientHandler)}";
 
+		private static readonly System.Net.Http.HttpMethod Patch = new System.Net.Http.HttpMethod("PATCH");
+
 		private RequestDataHttpClientFactory HttpClientFactory { get; }
 
 		public int InUseHandlers => HttpClientFactory.InUseHandlers;
@@ -430,19 +431,17 @@ private static async Task SetContentAsync(HttpRequestMessage message, RequestDat
 			}
 		}
 
-		private static System.Net.Http.HttpMethod ConvertHttpMethod(HttpMethod httpMethod)
-		{
-			switch (httpMethod)
+		private static System.Net.Http.HttpMethod ConvertHttpMethod(HttpMethod httpMethod) =>
+			httpMethod switch
 			{
-				case HttpMethod.GET: return System.Net.Http.HttpMethod.Get;
-				case HttpMethod.POST: return System.Net.Http.HttpMethod.Post;
-				case HttpMethod.PUT: return System.Net.Http.HttpMethod.Put;
-				case HttpMethod.DELETE: return System.Net.Http.HttpMethod.Delete;
-				case HttpMethod.HEAD: return System.Net.Http.HttpMethod.Head;
-				default:
-					throw new ArgumentException("Invalid value for HttpMethod", nameof(httpMethod));
-			}
-		}
+				HttpMethod.GET => System.Net.Http.HttpMethod.Get,
+				HttpMethod.POST => System.Net.Http.HttpMethod.Post,
+				HttpMethod.PUT => System.Net.Http.HttpMethod.Put,
+				HttpMethod.DELETE => System.Net.Http.HttpMethod.Delete,
+				HttpMethod.HEAD => System.Net.Http.HttpMethod.Head,
+				HttpMethod.PATCH => Patch,
+				_ => throw new ArgumentException("Invalid value for HttpMethod", nameof(httpMethod))
+			};
 
 		internal static int GetClientKey(RequestData requestData)
 		{
diff --git a/tests/Tests/Connection/Http/HttpConnectionTests.cs b/tests/Tests/Connection/Http/HttpConnectionTests.cs
new file mode 100644
index 0000000000..cdcca5a359
--- /dev/null
+++ b/tests/Tests/Connection/Http/HttpConnectionTests.cs
@@ -0,0 +1,61 @@
+using System;
+using System.Net.Http;
+using FluentAssertions;
+using OpenSearch.Client;
+using OpenSearch.Net;
+using OpenSearch.OpenSearch.Xunit.XunitPlumbing;
+using Xunit;
+using HttpMethod = OpenSearch.Net.HttpMethod;
+
+namespace Tests.Connection.Http;
+
+public class HttpConnectionTests
+{
+	private static readonly System.Net.Http.HttpMethod Patch = new System.Net.Http.HttpMethod("PATCH");
+
+    private class MockHttpConnection : HttpConnection
+    {
+        public HttpRequestMessage LastRequest { get; private set; }
+
+        protected override HttpRequestMessage CreateHttpRequestMessage(RequestData requestData)
+        {
+            LastRequest = base.CreateHttpRequestMessage(requestData);
+            return LastRequest;
+        }
+
+		public override TResponse Request<TResponse>(RequestData requestData)
+		{
+			CreateHttpRequestMessage(requestData);
+			return new TResponse();
+		}
+	}
+
+    public static TheoryData<HttpMethod> HttpMethods()
+    {
+        var data = new TheoryData<HttpMethod>();
+        foreach (var httpMethod in Enum.GetValues<HttpMethod>()) data.Add(httpMethod);
+		return data;
+    }
+
+    [TU]
+    [MemberData(nameof(HttpMethods))]
+    public void UsesCorrectHttpMethod(HttpMethod method)
+    {
+        var mockHttpConnection = new MockHttpConnection();
+        mockHttpConnection.Request<StringResponse>(new RequestData(method, "", null, null, null, null));
+		mockHttpConnection.LastRequest.Method.Should().Be(ConvertHttpMethod(method));
+    }
+
+    private static System.Net.Http.HttpMethod ConvertHttpMethod(HttpMethod httpMethod) =>
+        httpMethod switch
+        {
+            HttpMethod.GET => System.Net.Http.HttpMethod.Get,
+            HttpMethod.POST => System.Net.Http.HttpMethod.Post,
+            HttpMethod.PUT => System.Net.Http.HttpMethod.Put,
+            HttpMethod.DELETE => System.Net.Http.HttpMethod.Delete,
+            HttpMethod.HEAD => System.Net.Http.HttpMethod.Head,
+            HttpMethod.PATCH => Patch,
+            _ => throw new ArgumentException("Invalid value for HttpMethod", nameof(httpMethod))
+        };
+
+}